<div>The purpose of this study was to evaluate the role of practice variability, through prosodic variation during speech sound training, in biofeedback treatment for children with childhood apraxia of speech. It was hypothesized that variable practice would facilitate speech sound learning.</div><div><b><br></b></div><div><b>Supplemental Material S1.</b> Sample video of prepractice. Prepractice included verbal and visual instruction to help the participant understand what was required for a correct production of the target movements.</div><div><br></div><div><b>Supplemental Material S2.</b> Sample video of the no prosody practice condition with ultrasound visual feedback. In this condition, the structured practice followed the same progression but with no intentional manipulation of prosody. The target words were modeled with a neutral tone so as not to draw the participants’ attention to prosody.</div><div><br></div><div><b>Supplemental Material S3. </b>Sample video of the prosody practice condtion with ultrasound visual feedback. In this condition, participants were told that they were going to practice the target utterances with different prosodic cues or “voices.”</div><div><b><br></b></div><div><b>Supplemental Material S4.</b> Individual within-session practice trial data in two treatment conditions. For each session, 20 min were spent on prepractice and practice of each treatment target (10 min with the ultrasound and 10 min without). As described above, participants transitioned from prepractice to practice only when the preestablished criteria were met.</div><div><br></div><div>Preston, J. L., Leece, M. C., McNamara, K., & Maas, E. (2017). Variable practice to enhance speech learning in ultrasound biofeedback treatment for childhood apraxia of speech: A single case experimental study. <i>American Journal of Speech-Language Pathology, 26, </i>840–852<i>. </i>https://doi.org/10.1044/2017_AJSLP-16-0155</div>